Stepper motor speed control and speed measuring system generally adopts ARM as a controller, and discrete digital logic circuit and analog circuit. The system with LPC2148 as control core, reasonable choice of motor frequency control and closed loop feedback control, real-time detection and adjust the speed of the motor, make the system not only has good steady-state performance, and has good dynamic performance. The system is mainly composed of LPC2148 based as the core of main control circuit connected motor drive circuit, communication module circuit,RS232), speed measuring circuit (Hall sensor), A/D conversion circuit and other circuit, as shown in figure l. Figure 2 for the ARM main control chip. LPC2148 as the core of the control circuit is responsible for the frequency output, by changing the frequency to control motor speed, the size of the data can be through the RS - sampling circuit232 interface circuit and PC communication. LPC2148 module to process the data will be collected at the same time, according to a further correction frequency deviation control signal output. The system of stepper motor's speed by adjusting the frequency method. Stepper motor speed 60/200 = f (x, where x is the multiple segmentation, subdivided driving mode, due to the interval Angle is small, the stepper motor control precision is improved obviously, at the same time this kind of drive mode and can effectively restrain noise of low speed running and oscillation phenomenon. 8 ° of two phase four type, 200 stepper pulse can turn a circle. Its stepping motion controlled by the ARM, the special motor drive L298 to drive of stepping motor, drive circuit is shown in figure 3. L298 contains 4 channel logical drive circuit, is a kind of two and four phase motor dedicated driver. Which contains two H bridge both high voltage large current bridge driver, receiving standard TTL logic level signal, can drive motor under 46 V, 2 A. ARM is main controller through the right to control access to the mouth, and M1 ~ M4 that four ports used to connect the motor, by right of the input pulse signal changes on its control. Hall effect a length l and width for b, d thickness of semiconductor chips, when it is placed in a magnetic induction intensity for magnetic field b, if in its opposite sides circulation control current I, and the orthogonal direction of the magnetic field and current direction, the other sides in the semiconductor will produce a and the control current of electric potential and magnetic induction intensity b is directly proportional to the product I, UH, UH = KHIB, namely the KH for the sensitivity of hall element, the electric potential is called the hall voltage, the semiconductor wafer is hall element, its size and external magnetic field and electric current is proportional to the. Hall switch sensor due to its small volume, non-contact, good dynamic performance, long life and other characteristics, widely used in the measurement of rotating object rotation speed field. Here choose SPRAGUE wrote the company produces the hall speed sensor, it is a kind of silicon monolithic integrated circuit, its internal voltage regulation circuit, hall voltage generator, amplifier, schmidt triggers and open collector output circuit, with wide working voltage range, high reliability, simple external circuit, the output level can be compatible with all kinds of digital circuits, etc. the main products: stepper motor, brushless motor, servo motor, stepping motor drive, brake motor, linear motor and other kinds of models of the stepper motor, welcome to inquire. Telephone:
